Yes, the four existing fan attaching holes are used to attach the bolt-on pulley. I face off the front of the pulley hub the thickness of the add-on pulley so there's no change in the position of the belt. I usually use a 2-groove pulley for a Ford 302 V8 and bore its center hole and slot the mounting holes to fit the hub of the 216 pump.
Jerry
Great information. I may try this when i remove the old water pump.
Thanks
